In response to a growing number of mumps outbreaks over the last decade, CDC has commissioned a work group to assess whether to add an additional dose to the current two-shot mumps vaccination regimen.
Mumps infections nearly tripled in 2016. What's the cause?
According to the Washington Post's "To Your Health," the work group is scheduled to present its recommendations to the CDC's Advisory Committee on Immunization Practices (ACIP) in February 2018.
Mumps cases on the rise in the US
More than 5,000 cases of mumps were reported in 2016 in the United States—the most cases of the virus reported in more than a decade, "To Your Health" reports. In comparison, the United States reported 1,329 cases in 2015 and 229 in 2012.
Arkansas, Illinois, Indiana, Iowa, Massachusetts, New York, and Oklahoma all reported more than 100 cases last year. In addition, according to "To Your Health," Arkansas has been fighting an outbreak that started in one community last summer and has since spread to 2,815 individuals. Nineteen of the recent outbreaks have occurred on college campuses, where large numbers of students often study, exercise, and live together in close quarters—creating ideal conditions for the virus' spread.
Unlike outbreaks of measles and whooping cough, which have occurred in populations that included significant numbers of unvaccinated people, the recent mumps outbreaks have happened in communities with high rates of immunization and among people who have received both recommended doses of the vaccine, "To Your Health" reports.
While most patients recover in a few weeks, mumps can produce serious complications including deafness and inflammation of the testicles, brain, or ovaries.
According to "To Your Health," the United States initiated its mumps vaccination program in 1967, when about 200,000 cases were reported annually. Even given the recent outbreaks, cases of mumps have declined by 99 percent compared with the pre-vaccination era, "To Your Health" reports.
CDC currently recommends that children receive their first dose of the measles, mumps, and rubella (MMR) vaccine at 12 to 15 months and then a second dose between ages 4 and 6.
For a person who receives two doses, the MMR vaccine is about 88 percent effective at preventing mumps, while a single dose is 78 percent effective at preventing mumps. A single dose is 97 percent effective at preventing rubella, and the two doses are 97 percent effective at preventing measles. Officials consider third dose
ACIP formed the mumps work group to look into issues related to the outbreaks including the duration of immunity and evidence on benefits of third dose, "To Your Health" reports.
Mona Marin, a viral disease expert for CDC, on Thursday told ACIP that data on both those topics are limited. She also pointed out that waning immunity does not fully explain why mumps cases have increased among 18- and 19-year-olds but not among older college students.
Marin added that state and local governments are especially interested in the potential for the additional dose as a preventive measure. "Although the disease has not been serious, the disruption and expense it has caused for local and state health officials has been significant," Marin said.
According to "To Your Health," Arkansas has used a third dose of the MMR vaccine in schools to cut further transmission. Dirk Haselow, a state epidemiologist said, "This booster dose has worked exceptionally well." He added that the incidence of severe complications from mumps has reduced considerably, particularly among vaccinated adults and children (Sun, "To Your Health," Washington Post, 2/23).
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